Characterization and energy recovery from biomass wastes

Abstract

The rise in energy demand, underutilization of resources, and the challenge of identifying suitable energy sources are critical issues, particularly in developing countries. Given these issues, this research aimed to characterize groundnut shell (GNS) and pinewood chips (PWC) biomass using thermal, combustion, FTIR, SEM, EDX and downdraft gasifier tests in order to assess the suitability of these biomass sources for gasification in Uganda. Results indicate that the volatile matter (VM) of GNS and PWC were 67.40 wt% and 71.88 wt%, respectively. Due to its higher VM, PWC vaporized before combustion, resulting in faster burning due to its high oxidation state compared to GNS. GNS had relatively high fixed carbon (FC), moisture content (MC), and ash contents were compared to PWC, resulting in higher amounts of char deposit during gasification. The calorific values obtained were ∼18.87 MJ/kg for GNS and ∼17.04 MJ/kg for PWC. The major decomposition peaks appeared between ≥348 °C to ≤640 °C for GNS and ≥316 °C to ≤620 °C for PWC, which led to an average weight loss of 61 % and 65.78 %, respectively. The morphological image of PWC shows the presence of granules, independent behavior and fibrous growth inside the carbon compared to GNS. Both samples formed conjugated structures due to isomerization, which stabilizes the bonds when the oxidation degradation between the double bonds occurs at the saturated carbon. GNS had a firepower of 5.07 kW at a burning rate of 17.338 g/min, which is ∼26.2 % higher than that of PWC. PWC had a lower energy consumption per unit time of 221.225 kJ/min than GNS, due to a test time reduction of ∼58 s and a lower energy density in the biomass fuel.